Various pressure relief devices for inflatable tires have been proposed in the prior art. U.S. Pat. No. 3,830,249 discloses a device in which a pressure relief ball is maintained in a seated position by a force applied by a compression spring until the air pressure within the tire exceeds a set pressure. When the set pressure has been exceeded, the pressure relief ball is unseated from the body, and surplus air escapes from the tire via the pressure relief device.
U.S. Pat. No. 4,660,590 is concerned with an inflation pressure regulator with a substantially friction-free flexing seal arrangement within a housing of the regulator which bypasses the tire when the pressure within the tire reaches a predetermined level. A sealing section of a flexure member is normally urged into sealing contact with a seat surface owing to the force exerted against the flexure member by a spring/ring combination. When the tire has been inflated to the pressure rating of the regulator, the pressure in a first chamber in the housing will exert sufficient force against the upper face of the flexure member to cause a flexing in a portion thereof and a consequential movement of the sealing section away from the seat surface, allowing air to escape via an exhaust aperture.
A further device is known from U.S. Pat. No. 6,125,694, which discloses an audibly reporting pressure-relief, automatic tire assembly for use in interaction with preexisting valve core stems on a tire.
WO 2005/042277 discloses a pressure relief device comprising a ring-shaped resilient member which is contractively fitted around an outer surface portion of a body of the device, whereby the resilient is stretched to relieve air when the air pressure inside the body exceeds a predetermined level.